Fire-box and grate.



MMQW MM mmm) AUG. QQ, 190.5.

C. W. JEWETT.

PIRE BOX AND GRATE. APPLIGATION NTD Maza, 1904.

IAVE/7705 C//HHLEJ N. IEA/ETT @Wwf PM/ PATENTBD AUG. 29, 1905.

C. W. JEWETT.

PIRE BOX AND GRATE,

APPLICATION FILED APR.23, 1904.

M. Mw .n m. m w www ANDREW. B. GRAHAM co., Pummnpawnins. wnsmnmou, n, c,

No. 798,417. PATENTED AUG. 29. 1905. C. W. JEWETT.

FIRE BOX AND GRATE.

APPLICATION 'FILED Amma, 1904.

J 3. \Q N E W Mw NWN m s s w ow w 3 Q l CHARLES W. JEWETT, OF BLACKDUCK,MINNESOTA.

FIRE-BOX AND GRATE.

Specification of Letters Patent.

Patented Aug. 29, 1905.

Application filed April 23, 1904:. Serial No. 204,614.

T a/ZZ whom, it 7mo/y concern:

Be it known that I, CHARLES W. JEWETT, of Blackduck, Beltrami county,Minnesota, have invented certain new and useful Improvements inFire-Boxes and Grates, of which the following is a specification.

In the operation of a wood-burning boiler great diiculty has been and isnow experienced in burning and keeping up steam with semidry orfreshly-cut green wood, and some kinds of such wood have been found tobe absolutely unfit for use in the lire-box of an ordinary boiler. Theresult is that steam plants using wood-burning boilers, particularlywhen located in sections of the country where green wood is much moreplentiful than dry, have found it necessary in the successful operationof the plant to keep a large supply of dry wood on hand, in whichaconsiderable amount of money must constantly be invested.

The primary object, therefore, of my invention is to provide a lire-boxand grate wherein semidry and green or wet wood can be readily burnedwithout reducing the steamgenerating capacity of the boiler or entailingadditional labor upon the fireman.

A further object is to effect a savingin the amount of fuel consumed,provide better combustion in the lire-box, and reduce the quantity ofashes resulting therefrom.

A further object is to prevent the boilerfront and grate from becomingoverheated and burning out, thereby effecting a large saving in theannual expense of running a steam plant.

A further object is to reduce the radiation of heat from theboiler-front and render the boiler-room more comfortable for thoseemployed therein.

Further objects of the invention will appear from the following detaileddescription.

The invention consists generallyin providingacomparatively largefire-box and closing the grate-surface therein, leaving onlyacomparatively small open area near the middle of i the grate and box.

Further, the invention consists in providing means for cutting off theHow of air through the open section of the grate.

Further, the invention consists in various constructions andcombinations, all as hereinafter described, and particularly pointed outin the claims.

Inthe accompanyingdrawings,forming part of this specification, Figure 1wis a longitudinal verticalv section of a boiler-setting and grateembodying my invention, the boiler being shown in elevation. Fig. 2 is ahorizontal section on the line rc a of. Fig. 1. Fig. 3 is a verticaltransverse section on the line g/ y of Fig. 1. Fig. l is a detailsectional view showing the grate-section in the firebox. Fig. 5 is aplan view of the same. Fig. 6 is a detail transverse section of thegrate, showing the damper in its closed position. Fig. 7 is a detailsectional view showing the damper in its open position. Fig. 8 is asection on the line .e a of Fig. 6.

In the drawings, 2 represents a boiler of ordinary type, and 3 theboiler-front, having the usual fuel and ash-pan openings I and 5.

6 is a fire-box of more ample dimensions than usual in apparatus of thiskind, having at each end abutment-walls 7, supporting angle-bars 8,whereon the grate is arranged.

I have shown the grate composed of three sections, two on the outside,represented by reference-numeral 9, and an intermediate-section 10. Allof these grate-sections are preferably dropped from six to ten inchesbelow the normalgrate-level in a boiler of this type, and the twooutside sections are below the level of the middle one and covered withfirebrick 11, whose upper surface is flush substantially with the top ofthe middle section. (See Fig. l.) These brick effectually close theoutside grate-sections against the passage of air and also prevent airfrom entering the fire-box between the grate and a wall12, thatseparates the fuel and ash-pan openings. The middle grate-section isopen to allow the entrance of air into the lire-box and extends the fulllength of the grate from one side of the fire-box to the other at rightangles to the usual arrangement of a grate in a boiler-setting. Theeffect of this arrangement is to form a close air-tight floor above thegrate, leaving only a space open in the middle of the grate and aboutone-third of its width and above the middle of the ash-pan 13 beneath.

A bridge-wall 14: is provided on the back side of the fire-box, risingto a point near the bottom of the boiler, the area of thespace be- IOOtween said wall and boiler being substantially that of the open sectionof the grate, as I have found this proportion to be productive of thebest results. Back of the bridge-wall I provide the usual combustion-chamber 15. I have found, however, that a greater portion of thecombustion will take place within the fire-box.

rIhe effect of closing the surface of the grate on each side of a narrowopening extending through the middle thereof is to very materiallyincrease the natural draft and produce a quicker and more perfectcombustion of the fuel. The air rushing through the opening in the gratewill have the eect of a forced draft, and I am able to burn wet or greenwood and easily make and keep up steam in a boiler with such wood as afuel as cannot be successfully burned in a boiler-grate of ordinaryconstruction. The bridge-wall is higher than it is ordinarily built andserves to confine the products of combustion in the lirebox and causesthe better consumption of the gases therein and conserves a considerableportion of the heat energy that is usually wasted. The air risingthrough the limited open area of the grate will keep the bottom of thebars cool at all times and prevent them from becoming overheated andburning out. With a strong draft, such as is created in a fire-box andgrate of this type, there will be less radiation toward the front of theboiler, and consequently it will not become overheated and burned out,and the expense of maintaining a plant of this kind will be considerablyreduced and the temperature of the boiler-room will be far morecomfortable th an such rooms ordinarily are.

It is desirable in an apparatus of this kind to provide some means forregulating' the flow of air through the open grate-section, and Itherefore provide a series of depending iianges 16, one preferably ateach end and one in the middle of the open grate-section. Between theselianges I provide dampers 17, having studs 18 journaled in said fiangesand provided with depending arms 19, to which horizontally-arrangedoperating-rods 20 are attached. Notched handle-bars 2l are pivotallyconnected to the outer ends of said bars and are arranged to slide overa plate 22 in the side Wall of the ash-pan opening. The dampers areadapted to swing up under the side bars of the open grate-section andclose the space between them against the passage of air, and therebyreduce temporarily the open area of the grate, and by thiscontrivancethe person in charge can readily regulate the draft according to thecondition of the fire and the character of the fuel beingI used.

In the operation of the apparatus the fire having been built on the opengrate-section and the dampers properly adjusted will as the fuel isadded spread over the closed area of the grate until abed of coals isformed thereon and kept alive by the air-currents through the opensection and from the freshly-supplied fuel.

I have found that any kind of wood can be burned in a fire-box of thistype and that not only a cheaper grade of fuel can be used, but a lessquantity will be needed to generate the required pressure of steam, andI attribute this result to the better combustion that takes place in thelire-box. I have also found that less labor is required to keep up thenecessary pressure of steam and that the expense of fuel is not onlyconsiderably reduced, but the incidental expense for repairs arisingfrom the overheating of the grate and'boilerfront is very much less thanusual in a plant of this kind.

\ I have shown a grate structure upon each side of the open section; butit will be understood without illustration that any other suitablesupport for this fire-brick may be employed Without departing from myinvention, which consists, essentially, in providing a firebox Hoor withareas closed against the passage of air and an area that is open to thepassage of air.

I claim as my invention- 1. A lire-box having side walls and a frontwall provided with fuel and ash-pit openings, and a bridge-Wall in therear of said box opposite said openings, in combination withgrate-sections supported by said side walls and having an openingextending across the box from one side wall to the other, there beingiioors of refractory material such as lirebrick on each side of saidsections and on substantially the same level thereof, and the area ofthe opening in said grate-sections being substantially the same as thearea of the passage above said bridge-wall, substantially as described.

2. The combination, with a fire-box having fuel and ash-pit openings, ofan open gratesection arranged near the middle of said box and extendingtransversely thereof from one side wall to the other, imperforate floorsof refractory material such as fire brick provided on each side of saidopen grate-section and on substantially the same level as said opensection and extending across the fire-box from one side wall to theother, and dampers arranged beneath the forward and rear edges of saidopen grate-section and arranged to cut off' the passage of air throughthe same, and means for operating said dampers, substantially asdescribed.

3. The combination, with a fire-box having fuel and ash-pit openings, ofan open gratesection arranged near the middle of said box and extendingfrom one side wall to the other, said section being composed of a seriesof bars 10, the forward and rear bars being provided on their under sidewith depending lugs, dam- IOO IIO

'pers hinged in said lugs and adapted to be swung up against the undei`side of said bars to regulate the passage of air through the same, bars9 provided upon each side of said loars 10 and below the level thereofand also extending from one side of the wall of the {ire-box to theother, and lire-bricl 1l supported upon said bars 9 and closing them tothe passage of air, and the top of said lirebricks being on a levelsubstantially with the IO top of said bars l0, substantially asdescribed and for the purpose specified.

In witness whereof I have hereunto set my hand this 30th day of March,1904.

CHARLES W. JEWETT. In presence of- M. D. SToNER, C. Gr. JOHNSON.

